Uplink precoding indication method and communication apparatus

Abstract

This application provides an uplink precoding indication method including: sending first indication information and third indication information when a quantity of uplink transmission layers of a terminal device is less than or equal to X; or sending first indication information, second indication information, and third indication information when a quantity of uplink transmission layers is greater than X, where the first indication information indicates an index of a first codeword in a first codebook and a quantity of uplink transmission layers of the first codeword, the second indication information indicates an index of a second codeword in the first codebook and a quantity of uplink transmission layers of the second codeword, the third indication information indicates that the quantity of uplink transmission layers of a terminal device is greater than X, and the second codeword and the first codeword have a same coherent capability.

What is claimed is: 
     
         1 . An uplink precoding indication method, comprising:
 obtaining a first codebook;   determining first information when a quantity of uplink transmission layers of a terminal device is less than or equal to X, wherein the first information comprises first indication information and third indication information, the first indication information indicates an index of a first codeword in the first codebook and a quantity of uplink transmission layers of the first codeword, and the third indication information indicates that the quantity of uplink transmission layers of the terminal device is less than or equal to X; or   determining first information when a quantity of uplink transmission layers of a terminal device is greater than X, wherein the first information comprises first indication information, second indication information, and third indication information, the first indication information indicates an index of a first codeword in the first codebook and a quantity of uplink transmission layers of the first codeword, the second indication information indicates an index of a second codeword in the first codebook and a quantity of uplink transmission layers of the second codeword, the third indication information indicates that the quantity of uplink transmission layers of the terminal device is greater than X, and the second codeword and the first codeword have a same coherent capability; and   sending the first information, wherein the first information is used by the terminal device to determine an uplink precoding matrix, and X is any one of 1, 2, 3, and 4.   
     
     
         2 . The method according to  claim 1 , wherein when the quantity of uplink transmission layers of the terminal device is less than or equal to X, the first information further comprises fourth indication information, the fourth indication information indicates a first coefficient, and the first coefficient indicates a phase difference between a first half and a second half of transmit antenna ports corresponding to the uplink precoding matrix. 
     
     
         3 . The method according to  claim 2 , wherein the first information further comprises second indication information, the second indication information indicates an index of a second codeword in the first codebook and a quantity of uplink transmission layers of the second codeword, the quantity of uplink transmission layers of the first codeword is the same as the quantity of uplink transmission layers of the second codeword, and the second codeword and the first codeword have a same coherent capability. 
     
     
         4 . The method according to  claim 1 , wherein when the quantity of uplink transmission layers of the terminal device is greater than X, the first information further comprises fourth indication information, the fourth indication information indicates a first coefficient, and the first coefficient indicates a phase difference between a first half and a second half of transmit antenna ports corresponding to the uplink precoding matrix. 
     
     
         5 . The method according to  claim 1 , wherein the first codeword and the second codeword are selected from codewords whose quantities of uplink transmission layers are 1 to 4. 
     
     
         6 . The method according to  claim 1 , wherein when the quantity of uplink transmission layers of the terminal device is greater than 4, the second codeword or the first codeword is selected from codewords whose quantity of uplink transmission layers is 4. 
     
     
         7 . The method according to  claim 1 , wherein a sum of indication bit overheads of the first codeword, the second codeword, and the coefficient is a first value. 
     
     
         8 . A communication apparatus, comprising:
 a transceiver; and   at least one processor coupled to one or more memories storing programming instructions for execution by the at least one processor to perform operations including:   obtaining a first codebook;   determining first information when a quantity of uplink transmission layers of a terminal device is less than or equal to X, wherein the first information comprises first indication information and third indication information, the first indication information indicates an index of a first codeword in the first codebook and a quantity of uplink transmission layers of the first codeword, and the third indication information indicates that the quantity of uplink transmission layers of the terminal device is less than or equal to X; or   determining first information when a quantity of uplink transmission layers of a terminal device is greater than X, wherein the first information comprises first indication information, second indication information, and third indication information, the first indication information indicates an index of a first codeword in the first codebook and a quantity of uplink transmission layers of the first codeword, the second indication information indicates an index of a second codeword in the first codebook and a quantity of uplink transmission layers of the second codeword, the third indication information indicates that the quantity of uplink transmission layers of the terminal device is greater than X, and the second codeword and the first codeword have a same coherent capability; and   sending the first information, wherein the first information is used by the terminal device to determine an uplink precoding matrix, and X is any one of 1, 2, 3, and 4.   
     
     
         9 . The communication apparatus according to  claim 8 , wherein when the quantity of uplink transmission layers of the terminal device is less than or equal to X, the first information further comprises fourth indication information, the fourth indication information indicates a first coefficient, and the first coefficient indicates a phase difference between a first half and a second half of transmit antenna ports corresponding to the uplink precoding matrix. 
     
     
         10 . The communication apparatus according to  claim 9 , wherein the first information further comprises second indication information, the second indication information indicates an index of a second codeword in the first codebook and a quantity of uplink transmission layers of the second codeword, the quantity of uplink transmission layers of the first codeword is the same as the quantity of uplink transmission layers of the second codeword, and the second codeword and the first codeword have a same coherent capability. 
     
     
         11 . The communication apparatus according to  claim 8 , wherein when the quantity of uplink transmission layers of the terminal device is greater than X, the first information further comprises fourth indication information, the fourth indication information indicates a first coefficient, and the first coefficient indicates a phase difference between a first half and a second half of transmit antenna ports corresponding to the uplink precoding matrix. 
     
     
         12 . The communication apparatus according to  claim 8 , wherein the first codeword and the second codeword are selected from codewords whose quantities of uplink transmission layers are 1 to 4. 
     
     
         13 . The communication apparatus according to  claim 8 , wherein when the quantity of uplink transmission layers of the terminal device is greater than 4, the second codeword or the first codeword is selected from codewords whose quantity of uplink transmission layers is 4. 
     
     
         14 . The communication apparatus according to  claim 8 , wherein a sum of indication bit overheads of the first codeword, the second codeword, and the coefficient is a first value. 
     
     
         15 . A non-transitory computer-readable storage medium storing computer instructions, that when executed by at least one processor, cause the at least one processor to perform operations including:
 obtaining a first codebook;   determining first information when a quantity of uplink transmission layers of a terminal device is less than or equal to X, wherein the first information comprises first indication information and third indication information, the first indication information indicates an index of a first codeword in the first codebook and a quantity of uplink transmission layers of the first codeword, and the third indication information indicates that the quantity of uplink transmission layers of the terminal device is less than or equal to X; or   determining first information when a quantity of uplink transmission layers of a terminal device is greater than X, wherein the first information comprises first indication information, second indication information, and third indication information, the first indication information indicates an index of a first codeword in the first codebook and a quantity of uplink transmission layers of the first codeword, the second indication information indicates an index of a second codeword in the first codebook and a quantity of uplink transmission layers of the second codeword, the third indication information indicates that the quantity of uplink transmission layers of the terminal device is greater than X, and the second codeword and the first codeword have a same coherent capability; and   sending the first information, wherein the first information is used by the terminal device to determine an uplink precoding matrix, and X is any one of 1, 2, 3, and 4.   
     
     
         16 . The non-transitory computer-readable storage medium according to  claim 15 , wherein when the quantity of uplink transmission layers of the terminal device is less than or equal to X, the first information further comprises fourth indication information, the fourth indication information indicates a first coefficient, and the first coefficient indicates a phase difference between a first half and a second half of transmit antenna ports corresponding to the uplink precoding matrix. 
     
     
         17 . The non-transitory computer-readable storage medium according to  claim 16 , wherein the first information further comprises second indication information, the second indication information indicates an index of a second codeword in the first codebook and a quantity of uplink transmission layers of the second codeword, the quantity of uplink transmission layers of the first codeword is the same as the quantity of uplink transmission layers of the second codeword, and the second codeword and the first codeword have a same coherent capability. 
     
     
         18 . The non-transitory computer-readable storage medium according to  claim 15 , wherein when the quantity of uplink transmission layers of the terminal device is greater than X, the first information further comprises fourth indication information, the fourth indication information indicates a first coefficient, and the first coefficient indicates a phase difference between a first half and a second half of transmit antenna ports corresponding to the uplink precoding matrix. 
     
     
         19 . The non-transitory computer-readable storage medium according to  claim 15 , wherein the first codeword and the second codeword are selected from codewords whose quantities of uplink transmission layers are 1 to 4. 
     
     
         20 . The non-transitory computer-readable storage medium according to  claim 15 , wherein when the quantity of uplink transmission layers of the terminal device is greater than 4, the second codeword or the first codeword is selected from codewords whose quantity of uplink transmission layers is 4.